1. Field of the Invention
The present invention relates to an etching apparatus for manufacturing semiconductor devices, and more particularly to a dry etching apparatus using plasma.
2. Description of the Related Art
In recent years, semiconductor devices have been substantially developed as information media such as computers are rapidly popularized. Accordingly, semiconductor devices are required to operate at a high speed and to have a large storage capacitance.
In order to satisfy these requirements, semiconductor device fabrication technologies have been developed in the trend of improving degree of integration, reliability and response speed. Accordingly, requirements for fine process technologies such as etching for forming patterns, which is an important technology to improve the degree of integration of the semiconductor devices, tend to be very strict.
Etching is a technology of forming the patterns by removing a selected portion of the film on the semiconductor substrate. Recently, a dry etching apparatus using plasma is mainly used in the process of fabricating the semiconductor devices in which a width of circuit lines is 0.15 xcexcm or less.
The dry etching apparatus includes a chamber for performing a process for etching the film, a chuck on which the semiconductor substrate is placed, and a baffle plate which is mounted to enclose the periphery of the chuck and has a plurality of slits for discharging reaction byproducts created in etching a film and non-reacted gas.
The baffle plate and the chuck divide the chamber into a process region in which the etching process is performed and a vacuum region for making a vacuum in the process region. Further, the baffle plate maintains the uniform density of the plasma supplied to the process region to etch the film on the semiconductor substrate.
U.S. Pat. No. 6,176,969 issued to Park, et al. discloses a dry etching apparatus including a baffle plate capable of easily discharging a reaction byproduct and non-reacted gas. Korea Laid-open Patent Publication No. 2000-026347 discloses a dry etching apparatus having an insulating ring made of a ceramic material for protecting screws for use in fixing a baffle plate to a chamber. The ceramic material has an excellent resistance against a cleaning process.
Korean Patent No. 197,649 discloses a thin film deposition apparatus including a baffle plate fixed to a chamber for preventing expansion of plasma under low pressure.
Japanese Laid-open Patent Publication No. 2000-058518 discloses a plasma treating apparatus including a baffle plate in which an exhaust port is formed and a chuck on which a semiconductor substrate is placed.
A dry etching process performed by the dry etching apparatus will be described below.
An electrostatic chuck is provided in the chamber performing the dry etching process. The semiconductor substrate is placed on the chuck. A baffle plate having a plurality of slits is mounted along a peripheral surface of the electrostatic chuck. The electrostatic chuck and the baffle plate are upwardly and downwardly moved in the chamber. An upper electrode and a lower electrode are respectively mounted on an upper portion of the chamber and the electrostatic chuck in order to generate the plasma.
When the semiconductor substrate is carried in the chamber, the electrostatic chuck and the baffle plate are lowered to a position at which the semiconductor substrate is transported. After the semiconductor substrate is loaded on the electrostatic chuck, the electrostatic chuck and the baffle plate are elevated to a position at which the dry etching process is carried out.
In the dry etching process, an outer edge of the baffle plate faces an inner surface of the chamber. Accordingly, the process region in which the dry etching process is performed is defined by the inner surface of the chamber, the upper electrode, the baffle plate and the electrostatic chuck.
The upper electrode is connected to an etching gas supply part that supplies an etching gas in the dry etching process. When radio frequency electric power is applied to the upper electrode and the lower electrode, the etching gas supplied to the process region of the chamber is converted into a plasma phase.
A film coated on the semiconductor substrate is etched by the reaction between the plasma and the film. A reaction byproduct generated by the chemical reaction of the plasma with the film and a non-reacted gas are discharged through the slits formed in the baffle plate.
However, the reaction byproducts are not completely discharged from the process region and the remaining byproducts are attached to the inner surface of the chamber, the electrostatic chuck and the baffle plate which define the process region.
The reaction byproducts attached to the upper surface of the baffle plate and inner surfaces of the slits are exfoliated from the baffle plate by the changes in the pressure and air stream in the chamber when the baffle plate is moved upwardly and downwardly, and are dispersed in the chamber.
Furthermore, the reaction byproducts attached to the inner surface of the chamber are exfoliated from the outer edge of the baffle plate while the baffle plate is moved upwards and downwards and then dispersed in the chamber.
The exfoliated and dispersed reaction byproducts are fine particles, which act as a pollution material that is attached to and contaminates the semiconductor substrate during the process.
Accordingly, there are problems that the reliability and productivity of the semiconductor device is lowered and the working time of the etching apparatus is reduced due to a non-periodic maintenance and a repair step to remove the pollution material.
The present invention has been made to solve the aforementioned problem, and accordingly it is an object of the present invention to provide a dry etching apparatus that reduces the amount of pollution material created by the exfoliating of reaction byproducts that adhere to a chamber used for performing a dry etching process.
In accordance with the invention, there is provided a dry etching apparatus having a chamber into which a plasma gas for etching a film coated on a semiconductor substrate is provided in a plasma phase. In the chamber, a dry etching process is performed by using the plasma. A chucking apparatus for supporting the semiconductor substrate is disposed in the chamber, and is upwardly elevated to a predetermined position to perform the dry etching process and moved downwardly to load and unload the semiconductor substrate. A baffle plate discharges reaction byproducts created in the dry etching process and a non-reacted gas out of the chamber. The baffle plate has a flat ring shape and slits through which the reaction byproduct and the non-reacted gas are exhausted, and is fixed to an inner surface of the chamber so that a terminal end of the baffle plate faces a peripheral surface of the chucking apparatus at a predetermined position.
An one embodiment, a step portion on which the baffle plate is placed is formed along an inner surface of the chamber.
The dry etching apparatus may further include at least one pad for adjusting a mounting height of the baffle plate, the pad being disposed between the step portion of the chamber and the baffle plate. The pad can have a flat-ring shape and a thickness of 0.9 mmxcx9c1.1 mm. The pad is made of aluminum and the surface of the pad is subjected to an anodizing treatment to form a coating layer.
The dry etching apparatus preferably comprises a shield for protecting the inner surface of the chamber against the plasma for use in the dry etching process. The shield is disposed on the baffle plate to cover the inner surface of the chamber. The shield is made of aluminum, of which an inner surface is coated with a material subjected to an anodizing treatment.
A plurality of thru-holes are formed along an outer edge of the baffle plate and a plurality of screw-holes corresponding to the thru-holes of the baffle plate are formed on the step portion on which the baffle plate is placed so that screws fix the baffle plate to the chamber through the thru-holes of the baffle plate.
In another embodiment, both the pad and the shield have a plurality of thru-holes corresponding to the thru-holes of the baffle plate so as to be attached to the chamber by screws.
In the dry etching apparatus, since the baffle plate is mounted on the inner surface of the chamber so that the baffle plate does not to move upwards and downwards along with the chuck, the reaction byproduct adhered to the baffle plate is prevented from being exfoliated from the baffle plate. Accordingly, an amount of a pollution material caused by exfoliating of the reaction byproduct can be reduced.